Heat exchangers have uses in all industries across the world. The greatest difficulty with indirect-contact heat exchangers lies in fouling. Solids, liquids, or gases from the process fluid or the heating/cooling fluid can deposit on the walls, react with the walls, desublimate and deposit, or any number of other processes to coat the walls with foulants. Removal of these foulants while still operating the exchanger has been studied extensively. However, cryogenic heat exchange is a relatively young industry and foulant removal during operations is not as thoroughly studied. A unique difficulty in cryogenics is the desublimation or condensation and solidification of components in the process fluid onto the walls. Methods for removing these foulants center around melting the solids back into the process fluid. However, these techniques often involve shutting down coolant flow. Without coolant flow, the exchanger warms up due to process fluid, direct heat can be applied to the tubes/plates of the exchanger, or warm fluid can be passed through the coolant side. However, the ability to remove these foulants without shutting down either the process or coolant sides of the exchanger is needed.
Induction heaters are used when direct heating is difficult or impossible. Induction heaters can induce eddy currents in a conducting object, typically metals. This type of heating is used in furnaces, welding, cooking, brazing, sealing, and plastics processing. The inventors are unaware of any applications where induction heating is used to heat up metal in the walls of heat exchangers and thereby melt foulants off the walls.
U.S. Pat. No. 6,023,944, to Blundell teaches an apparatus and method for processing a sublimed material. A sublimed gaseous substance is directly contacted by a coolant fluid, causing the sublimed substance to desublimate and fall into a tank. The tank is at an elevated pressure such that, when the tank is heated, the desublimated solid melts to form a liquid. The heat may be supplied by various heaters, including induction heaters. The present disclosure differs from this prior art disclosure in that direct-contact heat exchange is used, solids formed are not deposited on a surface of the heat exchanger, and the induction heater is not used to melt the solids back into a process fluid, but rather are melted to form a product liquid. This prior art disclosure is pertinent and may benefit from the devices and methods disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.
U.S. Pat. No. 9,254,448, to Turner, et al., teaches a sublimation system and associated devices. A slurry is passed into a heat exchanger which vaporizes the fluid portion of the slurry. The vapor and the solids are then passed to a second heat exchanger, where the solids are sublimated. The present disclosure differs from this prior art disclosure in that the first heat exchanger provides heat to the slurry to vaporize the liquid, the solids are sublimated in the second heat exchanger rather than being melted back into the liquid, and induction heaters are not used. This prior art disclosure is pertinent and may benefit from the devices and methods disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.